Device for applying a homogeneously thick liquid layer over the working width of a material web

ABSTRACT

A device for applying a liquid as a thin continuous film to a passing workpiece strip has a runoff face and an intake face both extending a full width of the workpiece strip and meeting at an upwardly directed spillover weir. A diverter has a face juxtaposed with the intake face and forming therewith a storage compartment and a lip having a face juxtaposed with the runoff face at the spillover weir. Liquid is fed under pressure to the storage compartment so that the liquid rides up the intake face, over the spillover weir, and down the runoff face to a lower edge thereof whence it drops onto the passing workpiece strip. The lip face blocks any liquid that overshoots the spillover weir and deflects it back onto the runoff face.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase of PCT applicationPCT/EP2003/050857 filed 20 Nov. 2003 with a claim to the priority ofGerman patent application 10254793.9 itself filed 22 Nov. 2002, whoseentire disclosures are herewith incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a device for applying a wide liquid film inlaminar flow in even thickness over its working width to a continuouslyadvancing strip of goods. The device has a liquid reservoir that isrestricted on one side by a intake face that is inclined upward at anangle to the horizontal and extends the entire working width, which isfollowed in the downstream direction by a spillover weir and a runoffface connected thereto, from the bottom edge of which the overflowingliquid film runs off onto the strip of goods, and which is preferablyrestricted on the other side by an opposing intake face disposed abovethe first intake face and with a space therebetween. The liquidreservoir has a liquid intake region.

BACKGROUND OF THE INVENTION

A device of such kind is known from U.S. Pat. No. 5,887,459. Acharacterizing feature of that device is that the liquid is appliedevenly to a strip of goods as it advances. This is true initially forany quantity of a paint to be applied. However, it has been shown forlarger quantities that with necessarily thick liquid films the pressurefrom the feed pumps must be so great that the liquid separates from thesurface at the spillover weir. The liquid overshoots the spillover weir,and it is no longer possible to apply the liquid evenly over the workingwidth of the runoff face. This problem of constantly increasingkinematics to counter the effective gravity was observed for applicationquantities between 50 and 200 l/m/min. Of course, it also applies forlarger application quantities.

OBJECT OF THE INVENTION

The object of the invention is to improve an application device of thekind described in the introduction so that any volume may be distributedevenly over the working width in a given time unit.

SUMMARY OF THE INVENTION

To attain this object, according to the invention a diverter blockextending over the entire working width is attached to the spilloverweir or the runoff face to limit the flow rate. The effect of thisdiverter block is to slow and deflect the liquid rushing over thespillover weir, thus forcing it to run down on the runoff face at athickness that is predetermined via the adjustable diverter block.

According to above-cited U.S. Pat. No. 5,887,459, a divider comb isarranged inside the liquid reservoir and is designed to have a calmingand homogenizing effect on the liquid as it flows over the spilloverweir. In conjunction with the diverter block provided according to thepresent invention, which limits the film thickness of the flow area overthe entire working width, it is also advantageous if the free ends ofthis comb are curved in such manner that they extend over the spilloverweir and down onto the runoff face.

BRIEF DESCRIPTION OF THE DRAWING

The drawing is an exemplary illustration of a device according to theinvention. In the drawing:

FIG. 1 is a cross-section through the beam of the liquid-applicationmechanism with the diverter block attached to the beam,

FIG. 2 is a front view and cross-section of a divider comb arrangedinside the liquid reservoir and

FIG. 3 is a perspective view of the divider comb.

SPECIFIC DESCRIPTION

The liquid application device shown in FIG. 1 includes an angle bar 1forming an upwardly directed spillover weir 2. The leg that is inclinedupward toward the spillover weir 2 forms an intake face 3 forming thespillover weir 2 with a runoff face 4. The liquid film or layer forapplication flows in even distribution over these faces and drops offthe bottom edge 5 of runoff face 4 onto the workpiece strip 6.

A solid member 7, the liquid distribution mechanism, is attached inliquid-impermeable manner to the side of bar 1 on the intake face 3 andforms a liquid reservoir 8 adjacent the spillover weir 2. This liquidreservoir 8 is defined on one side by the intake face 3 and oppositelyby a face 9 of the liquid distribution element, which is arranged above,parallel to, and at a spacing from the intake face 3.

A liquid collecting space 10 is formed at the end of the liquidreservoir 8 opposite the spillover weir 2. It is fed by a plurality ofbores 11 that pass through the liquid distribution mechanism 7, and haveliquid inflow apertures 12 at the lower end of the liquid reservoir 8.

A liquid distribution mechanism 13 as described in U.S. Pat. No.5,243,841 is arranged at the opposite, upper end of bores 11.

It is normally sufficient if the stream of liquid that is pumped throughbores 11 flows to spillover weir 2 and from there flows downward overrunoff face 4. However, with large application quantities of 50 l/m/minand more there is a risk that the liquid distributed over the workingwidth of the application device may flow so quickly that the kinematicsexceed the force of gravity at the spillover weir 2. With such largequantities of liquid, it may happen that the liquid overshoots thespillover weir 2. To prevent this, a liquid diverter block 14 thatblocks the overshooting liquid extends the full length of theapplication device adjacent the spillover weir 2. It has a downwardlyprojecting lip 15 that forms a flow gap 16 with the runoff face 4. Bythis means, the advancing volume of liquid is forced to follow the pathover the spillover weir 2 collects upstream of the flow gap 16 and thenflows with the desired thickness and in the desired volume along therunoff face 4 over the entire width of the application device and ontothe goods 6.

Of course, the spacing of the liquid diverter block 14 is adjustable viascrews 17 that engage with member 7.

A divider comb 18 is arranged inside the liquid reservoir 8, and a lowermounting rail 19 thereof closes off the bottom the liquid reservoir 8.It is advantageous if the free ends 20 of the teeth of the divider comb18 are shaped to curve downward as shown in FIGS. 2 and 3. The curves atthe ends rest on the spillover weir 2. This curved shape of the combends 21 guides the liquid around the spillover weir 2 and assists withthe guidance of the application liquid onto the runoff face 4.

1. A device for applying a liquid as a thin continuous film to a passingworkpiece strip, the device comprising: a runoff face and an intake faceboth extending a full width of the workpiece strip and meeting at anupwardly directed spillover weir; a diverter having a face juxtaposedwith the intake face and forming therewith a storage compartment and alip having a face juxtaposed with the runoff face at the spillover weir;and means for feeding the liquid to the storage compartment so that theliquid rides up the intake face, over the spillover weir, and down therunoff face to a lower edge thereof whence it drops onto the passingworkpiece strip, the lip face blocking any liquid that overshoots thespillover weir.
 2. The device as cited in claim 1 wherein the diverteris a block that curves over the spillover weir.
 3. The device as citedin claim 1 wherein a height of the lip of the diverter is adjustable forinfluencing a flow volume alone the runoff face.
 4. The device asdefined in claim 1 wherein the diverter is a comb having an edge stripforming an upstream end of the storage compartment and a row of teethextending up along the intake face and over the spillover weir.
 5. Thedevice as defined in claim 4 wherein the teeth are L-shaped.
 6. Thedevice as defined in claim 1 wherein the faces are planar.
 7. A devicefor applying a liquid as a thin continuous film to a passing workpiecestrip, the device comprising: a runoff face and an intake face bothextending a full width of the workpiece strip and meeting at an upwardlydirected spillover weir; a diverter having a face juxtaposed with theintake face and forming therewith a storage compartment; means includingan array of bores opening into the storage compartment for feeding theliquid to the storage compartment so that the liquid rides up the intakeface, over the spillover weir, and down the runoff face to a lower edgethereof whence it drops onto the passing workpiece strip; and a combhaving a plurality of teeth extending up the intake face and over theweir and having free ends extending down along the runoff face at thespillover weir.
 8. The device defined in claim 7 wherein the teeth areL-shaped.